Thermal, Mechanical and Tribological Properties of Gamma-Irradiated Plant-Derived Polyamide 1010.

In this study, we investigated the influence of the gamma-irradiation dose and the addition of the cross-linking agent (triallyl isocyanurate (TAIC)) on the thermal, mechanical and tribological properties of plant-derived polyamide 1010 (PA1010). PA1010 and PA1010/TAIC were extruded using a twin screw extruder and injection molded. These specimens were then irradiated with gamma-ray in air with doses of 20 and 50 kGy. After gamma-irradiation, the specimens were heat-treated to remove the free radicals generated in the polymer. The combination of gamma-irradiation and the addition of TAIC significantly changed the crystal structures of PA1010. Glass transition temperature increased with the addition of TAIC and, in particular, with increasing gamma-irradiation dose. Moreover, PA1010/TAIC showed a rubbery plateau originating from cross-links by gamma-irradiation, which was observed in the temperature regions above the melting point in DMA measurements. Mechanical properties such as strength, modulus and hardness, and tribological properties such as frictional coefficient, specific wear rate and limiting pv (pressure p × velocity v) value of PA1010 improved with change in the internal microstructure with the gamma-irradiation and addition of TAIC.

Circulating pancreatic cancer exosomal RNAs for detection of pancreatic cancer.

Diagnostic biomarkers for the early diagnosis of pancreatic cancer are needed to improve prognosis for this disease. The aim of this study was to investigate differences in the expression of four messenger RNAs (mRNAs: CCDC88A, ARF6, Vav3, and WASF2) and five small nucleolar RNAs (snoRNAs: SNORA14B, SNORA18, SNORA25, SNORA74A, and SNORD22) in serum of patients with pancreatic cancer and control participants for use in the diagnosis of pancreatic cancer. Results were compared with the expression of sialylated Lewis (a) blood group antigen CA19-9, the standard clinical tumor biomarker. Reverse transcription quantitative real-time PCR showed that all of the mRNAs and snoRNAs, except CCDC88A, were encapsulated in exosomes and secreted from cultured pancreatic cancer cells, and present in cell culture medium. In a discovery-stage clinical study involving 27 pancreatic cancer patients and 13 controls, the area under the receiver operating characteristic curve (AUC) of two mRNAs (WASF2 and ARF6) and two snoRNAs (SNORA74A and SNORA25) was > 0.9 for distinguishing pancreatic cancer patients from controls; the AUC of CA19-9 was 0.897. Comparing serum levels of WASF2, ARF6, SNORA74A, SNORA25, and CA19-9 revealed that levels of WASF2 were the most highly correlated with the risk of pancreatic cancer. The AUCs of WASF2, ARF6, SNORA74A, and SNORA25 in serum from patients in the early stages of pancreatic cancer (stages 0, I, and IIA) were > 0.9, compared with an AUC of 0.93 for the level of CA19-9. The results of this study suggest that WASF2, ARF6, SNORA74A, and SNORA25 may be useful tools for the early detection of pancreatic cancer. Monitoring serum levels of WASF2 mRNA may be particularly useful, as it was the most highly correlated with pancreatic cancer risk.

Immobilization of a non-heme diiron complex encapsulated in an ammonium-type ionic liquid layer modified on an Au electrode: reactivity of the electrode for O2 reduction.

An unstable diiron(II,II) complex possessing O2 binding ability at low temperature was encapsulated and stabilized in an ammonium-type ionic liquid layer polymerized on an electrode. The encapsulated complex revealed catalytic reactivity for four-electron reduction of O2 at an ambient temperature in aqueous solution.

A phosphonium-type ionic liquid-modified Au electrode: a new platform for entrapping functional molecules on substrate surfaces.

The liquid state of a bulky phosphonium-type ionic compound with a disulphide group was used to modify a Au substrate with effective dispersion. The substrate incorporates external compounds into the vacant space formed inside the ionic liquid regardless of the net charge of the compounds without any direct bonding.

Preparation of collagen/gelatin sponge scaffold for sustained release of bFGF.

Artificial dermis (AD) has been used to regenerate dermis-like tissues in the treatment of full-thickness skin defects, but it takes 2 or 3 weeks to complete dermal regeneration. Our previous study demonstrated that injection of basic fibroblast growth factor (bFGF)-impregnated gelatin microspheres (MS) into the AD accelerates the regeneration of dermis-like tissue. However, injection of gelatin MS before clinical use is complicated and time consuming. This study investigated a new scaffold, in which collagen and gelatin are integrated, and which is capable of sustained bFGF release. We produced collagen/gelatin sponges with a gelatin concentration of 0wt%, 10wt%, 30wt%, and 50wt%. The mean pore size in each sponge decreased with the gelatin concentration. In an in vitro study, proliferation of fibroblasts in each sponge was not significantly different over 7 days of culture. As for in vivo sustained release of bFGF, a radioisotope study demonstrated that retention of bFGF in gelatin 10wt% and 30wt% sponges was significantly larger than that in gelatin 0wt% sponge. The collagen/gelatin sponges were grafted on full-thickness skin defects created on a rabbit ear, and we evaluated regeneration of dermis-like tissue by measuring the amount of hemoglobin and size of dermis-like tissue on histological sections. Seven days after implantation, the amount of hemoglobin in dermis-like tissue in gelatin 10wt% sponge was significantly larger than those in control and gelatin 50wt% sponge. Twenty-eight days after implantation, the area of dermis-like tissue in gelatin 10wt% sponge was significantly larger than those in the other specimens. We conclude that the collagen sponge integrated with 10wt% gelatin has the most potential for sustained release of bFGF and that the combination of collagen/gelatin 10wt% sponge and bFGF is a promising therapeutic modality for the treatment of full-thickness skin defects.

Three-dimensional cell seeding and growth in radial-flow perfusion bioreactor for in vitro tissue reconstruction.

Radial-flow perfusion bioreactor systems have been designed and evaluated to enable direct cell seeding into a three-dimensional (3-D) porous scaffold and subsequent cell culture for in vitro tissue reconstruction. However, one of the limitations of in vitro regeneration is the tissue necrosis that occurs at the central part of the 3-D scaffold. In the present study, tubular poly-L-lactic acid (PLLA) porous scaffolds with an optimized pore size and porosity were prepared by the lyophilization method, and the effect of different perfusion conditions on cell seeding and growth were compared with those of the conventional static culture. The medium flowed radially from the lumen toward the periphery of the tubular scaffolds. It was found that cell seeding under a radial-flow perfusion condition of 1.1 mL/cm2 x min was effective, and that the optimal flow rate for cell growth was 4.0 mL/cm2 x min. At this optimal rate, the increase in seeded cells in the perfusion culture over a period of 5 days was 7.3-fold greater than that by static culture over the same period. The perfusion cell seeding resulted in a uniform distribution of cells throughout the scaffold. Subsequently, the perfusion of medium and hence the provision of nutrients and oxygen permitted growth and maintenance of the tissue throughout the scaffold. The perfusion seeding/culture system was a much more effective strategy than the conventional system in which cells are seeded under a static condition and cultured in a bioreactor such as a spinner flask.

Preparation and properties of ProNectin F-coated biodegradable hollow fibers.

ProNectin F-coated biodegradable hollow fibers were newly prepared and their cytocompatibility was evaluated in vitro. Although the coating efficiency onto poly(L-lactic acid) (PLLA) and poly(lactide-co-caprolactone) [p(LA/CL)] matrices was similar, the cell adhesion properties were greatly affected by the nature of the polymer substrate. ProNectin F-coated PLLA showed about seven times higher cytocompatibility than ProNectin F-coated p(LA/CL). The single-extruded melt spinning method and the core-sheath bicomponent melt spinning method were employed to prepare PLLA hollow fibers. The effect of the spinning conditions, such as the melt draw ratio, spinneret temperature, and take-up speed, on the diameter and wall thickness of the spun fibers was studied in detail. For single-extruded melt spinning, a segmented type of spinneret was used, and the effect of the flow rate of nitrogen, which was confined in the hollow part of fibers, was studied. X-ray photographs of the drawn hollow fibers, clarified the significant molecular orientation, which was much higher than that in drawn solid PLLA fiber under identical drawing conditions. The morphology and mechanical properties of hollow fibers demonstrated an increase in the tensile strength and a decrease in the thickness of the PLLA wall with increased nitrogen flow rates and melt draw ratios for single-extruded melt spinning. These results indicate the unique characteristics of ProNectin F-coated PLLA hollow fibers, which can be successfully utilized as a biodegradable substrate.

Effect of chemical features and stability of polyplexes on their gene transfer efficiency.

Chemically modified poly-L-lysine (PL) derivatives with two essential features, which we have recently reported on, have been used to study key factors affecting transgene expression efficiency. PL derivatives having both of N epsilon-trimethyl lysine residue and 25 mole % serine residue showed enhanced transfection efficiency. When PL was modified in either way, no marked enhancement in gene expression was observed. These PL derivatives were found to be able to deliver plasmid DNA into nucleus of the transfected cells with a similar amount. Judging from the loss of EtBr fluorescence intercalating to DNA, the condensing tendency of the DNA were greatly affected by the sequence of the polypeptides used. This loose compaction seems to enhance the transgene expression because of an easy disassembly of the formed complexes or recognition of the DNA molecules in the complexes.